Apparatus for straining pulp



Oct. 8, 1929. B. DECKER APPARATUS FOR STRAINING PULP v Filed Dec. 27,192'? 2 Sheets-Sheet 1 Attorneys L. B DECKER 1,731,193

APPARATUS FR STRAINING PULP 2 Sheets-Sheet 2 Filed Dec.. 27, 1927 Emmi/Attorneys Patented Oct. 8, 1929 UNITED STATES LElMIUEL B. DECKER, OFKENOGAMI, QUEBEC, CANADA APPARATUS FOR STRAINING PULP Application filedDecember 27, 1927. Serial No. 242,761.

uid embodying the formation of an initial basic covering or matting ofrelatively coarse stock, about the exterior of which is gathered thefiner fibers separated from the liquid.

Another object of the invention is the provision of a process andapparatus wherein the coarse matting stock may be obtained directly onthe'machine so as to obviate the necessity of drawing the same from-thesystem.

Still another object of the invention is the provision of an apparatuswhich maybe efficiently employed as a stock thickener or decker.

A further object of the invention is the provision of an apparatus ofthe above character which will be relatively simple and durable ofconstruction and economical in operation.

Still another object of the invention is the provision of a machine ofthe above type which can be manufactured at a comparatively low cost.

Other objects and advantages of the invention will become apparent asthe description progresses.

In the accompanying drawing forming a part of this specification and inwhich like reference characters are employed to designate' correspondingparts throughout the same:

Figure 1 is a top plan view of tlie assembled machine constructed inaccordance with my invention, 1

Figure 2 is a vertical longitudinal section through the same,

Figure 3-is an enlarged longitudinal section through the cylinder,

. Figure 4 is an end elevation of the cylinder taken on the line 4-4 ofFigure 3,

Figure 5 is an enlarged detail section, and Flgure 6 1s a similar View.

Referring to the drawings, wherein for the purpose of illustration isshown a preferred embodiment of the invention, the numeral 10 generallydesignates a water receiving vat which is preferably of rectangular formand open at the top. The sides of the vat are provided with transverselyopposed recesses designed to receive therein a cylinder supporting shaft11. The forward wall of the vat is formed with an opening adjacent thebottom thereof designed to receive one end of an inlet conduit 12through which the white water is discharged into the vat. A verticalbaflle plate 13 is secured to the bottom of the vat adjacent the inlet.12 to break thecurrent of the water discharged through theinlet.

The cylinder supporting shaft 11 is of tubular construction and isdivided adjacent one end by a transverse partition 14 to provide avacuum chamber atone end and .a ventilating chamber at the opposed end.A pair of diametrically opposed partition win s 15 are formed on theexterior of the sha t 11, these wings projecting radially in ahorizontal plane and preferably having a tapered cross section. Securedto the tubular shaft 11 and depend; ing downwardly therefrom are aplurality of tubes 16 communicating with the interior of the shaft atone side of the partition 14 to rovide a suction manifold. At theopposed side of the partition 14 is mounted an upwardly extendingvertical tube 17 communicating with the ventilating side of the shaft topro vide a vertical ventilator.

Positioned concentrically about the shaft 11 is a relatively largecylindrical drum 18 enclosed at its ends by removable cylinder heads 19slidably fitted on the ends of the shaft 11.- The peripheral edge of theheads is rabbeted to provide .a reduced portion adapted to be snuglyfitted in the ends of the cylinder 18 and a diametrically enlargedflange adapted to abut the end edges thereof. The heads are secured onthe cylinder by means of axially extending screws 20 projecting throughopenings 'invthe flanges of the heads and threaded in the ends of thecylinder. Formed integral with or secured to the outer sides of theheads adjacent the peripheral edges thereof are annular external spurgears 21, the purpose of which will be later described. The intermediateexterior surface of the cylinder is'preferably recessed and adapted toreceive a spiral wire 22 about the exterior surface of which is secureda foundation screen wire 23 of relatively coarsamesh,

approximately fourteen mesh. An outside straining wire 24 is securedover the founda; tion wire 23, the outside wire being of finer mesh,preferably about sixty mesh. The wall of the cylinder 18 is perforatedto provide a plurality of longitudinally arranged apertures 25, eachsuccessive line of apertures being arranged in staggered relation inconformity with the spiral winding of the=wire 22. As shown to advantagein Figure3, the cylinder is disposed on the shaft llwithin the vat 10,the heads of the cylinder being spaced from the interior sides ofthe vatand rotatably fitted on the shaft by means of suitable ball or rollerbearings. A suitable packing 26 is also snugly fitted about the shaft 11to prevent leakage of the water through the heads.

As illustrated in Figure 2, the wings 15 are formed so that their outeredges terminate adjacent the interior periphery of the cylinder whilethe vertical tubes 16-and 17 terminate adjacent the upper and lowerportions thereof. The shaft 11 is rigidly held in fixed position in thevat by means of flanges 27 secured about the shaft and attached to thesides of the vat. Thecylinder is rotatable about the shaft and is drivenby a pair of.

pinion gears 28 fixed on a horizontal'drive shaft 29 and arranged tomesh with annular gears 21 mounted on the outer sides of the cylinderheads. The shaft 29 may be arranged in the upper rear portion of thevat, as indicated at Figure 2, and driven by any suitable motor.

Rotatably supported in a-horizontal position parallel with the cylinderis a couch roll 30 arranged to contact with the upper portion of theexterior cylinder screen. This'roll is covered with a felt or othersuitable jacketing, as it is customary, to remove the stock accumulatedon the cylinder screen,

The pulp isremoved from the couch roll 30 and discharged into a suitablereceiver by means of an angularly supported blade 31, commonly termed adoctor, arranged so that its upper bevelled edge contacts with the couchroll while the lower edge is inclined Y downwardly to discharge thestock into the receiver.

Removabl mounted in the upper forward portion of tie vat for supplying aquantity of coarse pulp during the operation of the strainer, is a stocktrough 32 supported in horizontal position upon apair of bars 33 fixedto the opposed inner sides of the vat and provided with an intermediatevertical partition 24 adapted to form a bafie for the stock. The innerends of the sides of the trough 32 are cut inarcuate form. so as'to bepositioned snugly against the upper portion of the cylinder, asindicated in Figure 2. The bottom of the trough terminates apredetermined distance from the cylinder, as clearly illustrated in thedrawing, to provide a feed slot by means of which the coarse pulpdischarged on to the cylinder screen is regulated so. as to form afoundation matting of coarse stock of predetermined thickness. A conduit35 is a connected to and communicates with the interior of the trough32, this conduit'being provided with a regulating valve 36 forcontrolling the supply of coarse stock to the trough.

Under the present practice, it is customary to mix a. quantity of coarsestock with the white water during the straining operation, the coarsepulp beingsecured from the output stock of the system. This may also beefii'ected in the present machine, the conduit 35 being in communicationwith a stock container for selectively securing a predetermined quantityof coarse pulp for the forma- 7 tion of the foundation matting. It isalso contemplated, however, to provide means whereb the coarse stock maybe obtained directly rom the white water employed in the vat, this beingaccomplished by providing an inclined strainer embodying a strainerframe 37 formed with a receiving trough 38;, at the upper end. Atransverse baiile 39 is mounted in the trough 38' and arranged so thatthe wao ter will be initially discharged through the lower portion ofthe trough and then directed upwardly by means of a vertical plate 40extending partially upward from thebottom of the trough. -An inclinedsifting screen 41, 105 of suitable mesh,.is mounted in an intermediateposition in the frame and arranged so that the coarser fibers from thewater will be delivered downwardly into the feed trough 32, the waterand finer fibers will pass through the screen and will be discharged,downwardly in a'lower conduit d2 into the 'vat. With this construction,a suitable supply of coarse ifibers can be secured from the white waterto form the foundation matting and 115 obviate the necessity of vwithdrawing the coarser stock from the system.

While the apparatus is particularly designed to be employed as asave-all for the recovery of the fine fibers from the white 12 water itis readily apparent that the same may be efliciently employed as a stockthickener, often called a decker, for strainin the stock during itscustomar course throng the system. In this particular application, the125 inclined strainer and trough 32 may be removed or entirelyeliminated from the construction to provide a stock thickener having anexceedingly eflicient induced suction whereby the pulp fibers may beeficiently ,130

drawn on to the cylinder in the thickening operation.

An important feature of the present process is the formation of aninitial layer or matting of relatively coarse pulp fibers on thestrainer screen. The finer fibers recovered from the white water arethen drawn about the exterior surface of the matting and thus strained.In this manner, it is possible to reclaim practically the entire finefiber residue in the white water.

i In the operation of the apparatus described in the foregoing, asuitable vacuum pump1s connected with one end of the tubular shaft 11 incommunication with the manifold tubes 16 arranged at one side of thepartition 14. The opposite end of the shaft is open to the atmosphere.The white water is delivered into the vat through the inlet 12 and ispreferably maintained at a level designated at 43 below the outlet inthe upper end of the vent tube 17. A supply of coarse stock isdischarged into the trough 32 by the application of-the inclinedstrainer mounted thereon or,

if desirable, directly through the supply pipe 35. The cylinder is thenuniformly rotated at a predetermined speed. The operation of the vacuumpump will produce a suction through one end of the shaft 11 and manifoldtubes 16 to exhaust the water from the lower portion of the cylinder.Due to the particular arrangement of the wings 15, the induced suctionwill be of greater efiect in the lower half of the cylinder inasmuch asthe water will form a water seal between the outer edges of the wingsand the opposed sides of the cylinder. In the upper end of the cylinder,above the water line, the admission ofair through the ventilator chamberand tube will offset the suction so that the stock may be readilyremoved.

During the operation of the machine, the cylinder rotates in thedirection indicated by the arrow in Figure 2, the coarse pulp fibersbeing drawn on to the exterior screen of the cylinder by the inducedsuction and the finer fibers from the white water adhering to theexterior surface of the coarse fiber matting during the continuingrotary movement of the cylinder. When the-stock drawn on the cylinderreaches a position above the water level and immediately prior to theengagement with the couch roller the induced suction created byexhausting the water from the cylinder is rendered practicallynon-efiective by the introduction of air in the upper portion of thecylinder thus enabling the couch roll to readily gather the stock fromthe surface of the cylinder. The upper portion of the cylinder moving incontact with the couch roll is then thoroughly washed as is customary.It will be particularly noted that the coarse stock supplied through thetrough 32 is drawn on to the washed portion of the cylinder as it wrotates below the water level. By this construction, the coarser fibersare initially positioned directly on to the exterior straining screenand the fine fiber residue in the white water subsequently drawn aboutthe matting so that an exceedingly high proportion of the residue isrecovered.

Thus, by the present process a foundation covering or matting of-coarsepulp fiber is formed by induced suction upon the straining screen priortothe collection of the finer fibers recovered from the white water.Furthermore, the supply of coarse fibers may be secured directly uponthe apparatus without the necessity of withdrawing the same from thetreated stock of the system.

It is to be understood that the form of my invention herein shown anddescribed is-to be taken as a preferred example of the same, and thatvarious changes as to the shape, size, and arrangement of parts mayberesorted to without departing from the spirit of the invention or thescope of the subjoined claims.

Having thus described my invention, I claim 1. In an apparatus forstraining pulp fibers including a vat adapted to contain white water, ahollow shaft extending through the vat, the said shaft being divided toform separated chambers, a perforated cylinder mounted for rotarymovement about the said shaft, suction tubes connected to andcommunicating with one chamber of the shaft and depending downwardlywithin the cylinder for exhausting the water from the cylinder, aventilating tube connected to the shaft and communicating with theopposed 01121111 ber extending vertically upward within the cylinder tosupply air into the upper portion of the cylinder above the water line,and means for removing the stock drawn upon the exterior of thecylinder.

2. In a straining apparatus of the character described, a vat, a hollowshaft supported in stationary position in the vat, the said shaft beingdivided by a transverse partition to form a suction chamber at one endand a ventilating chamber at'the opposite end, a perforated strainingcylinder rotatably mounted on the shaft enclosed at its ends, aplurality of suction tubes connected to the vacuum chamber of the shaftand depending downwardly within the cylinder, the said tubes connectingwith said vacuum chamber and open at their lower ends, a ventilatingtube secured to and communicating with the ventilating chamber of theshaft and projecting upwardly therefrom, the upper end of the saidventilating tube being open and terminating adjacent the inner tubeportion of the cylinder, and a pair of diametrically opposed wingsextending radially from the shaft in.

3. In combination, a vat, a rotary straining cylinder, a shaft on whichsaid cylinder is supported, a pair of wings extending from said shaftadapted to divide the interior of the cylinder into a pair of opposedcompartments, means for exhausting fluid from one of the compartments,and means for introducing air to the opposed compartment.

4. In combination a vat, a rotary straining cylinder, a shaft onwhichsaid cylinder is supported, partitions projecting outwardly fromsaid shaft and terminating adjacent the interior walls of the cylinder,means for exhausting fluid from one compartmentin the cylinder throughthe shaft, and means for introducing air into a compartment in thecylinder through said shaf 5. In combination, a vat, a rotary strainingcylinder, a shaft on which saidcylinder is supported, a pair ofhorizontally-extending wings projecting from the shaft and terminatingadjacent the inner Wall of the cylinder, means for exhausting the fluidfrom the lower interior portion of the cylinder, and

means for introducing air into the upper interior portion of thecylinder.

In witness whereof I have hereunto set my hand.

LEMUEL B. DECKER.

